1. Field of the Invention
The present invention is related to multi-media receivers and, in particular, to a multi-channel interface such as a high-definition multi-media interface.
2. Discussion of Related Art
High-definition multimedia is becoming increasingly common-place. Continuously, consumers are demanding greater levels of quality in multimedia entertainment. High-Definition Multimedia Interface (HDMI) refers to a technology that is being developed to allow the seamless transfer of uncompressed digital audio and video data between devices. HDMI is the first industry-supported, uncompressed, all-digital audio and video interface. HDMI is utilized to interface between devices such as digital set-top boxes, DVD players, and televisions, or any other device that transmit or receive digital audio and video data.
The HDMI standard supports standard, enhanced, and high-definition video, plus multi-channel digital audio on a single cable. Further, HDMI systems transmit all ATSC HDTV standards and can support 8-channel digital audio, with bandwidth to spare to accommodate future enhancements and requirements.
Conventionally, HDMI systems operate over a single cable through HDMI connectors, eliminating the need for the myriad of audio and video cables utilized in systems not utilizing HDMI technology. HDMI systems can support many formats of digital and non-digital television including high definition formats such as the 720p, 1080i, and 1080p formats. Baud rates in HDMI systems range from about 250 MHz to 1650 MHz. For data formats that do not require 250 MHz, pixel repetition is utilized to achieve the minimum 250 MHz baud rate. In addition, the HDMI technology is backwards compatible to the digital video interface (DVI) standard.
Conventional receivers for HDMI utilize an analog approach, equalizing with fixed equalization from a limited set of choices and providing for gross timing recovery from another set of limited choices. For example, it is not uncommon to have sets of three options for equalization and for timing recovery. This approach severely limits the performances of these receivers because of the inability to adapt to the operating environment of the system. This inability can become apparent in harsh environments, such as large attenuation across the cable or large amounts of timing jitter, or if the environment is changing due to, for example, temperature fluctuations or changes in the channel properties. Changes in channel properties can also occur, for example, through human interactions.
The lack of equalization options limits the ability of these receivers to provide the optimum amount of channel equalization, leading to significant degradation of the signal-to-noise ratio (SNR) of the receiver. Minimal timing recovery options limit the amount of jitter that the receiver can track and correct, further leading to a degradation of the performance of the receivers. Together, these issues lead to an increased bit-error rate (BER), limit the cable length over which the receiver can successfully operate, and limit the ability of the receiver to cope with poor connectors and low quality board materials.
Therefore, there is a need for better performing receivers to receive data over multi-channel systems.